Slow Speeds / Dropouts: nbn™ & Cable Internet Troubleshooting

These troubleshooting steps will help if your Optus Cable or nbn™ Broadband connection is dropping out or running slower than usual. For DSL connections, see Slow Speeds / Dropouts: DSL Broadband.

Before you start:

  • Visit Check Network Status > Outages > Fixed Outages to see any known issues with our network in your area
  • After each troubleshooting step, test your speed at
Step 1: Reduce simultaneous internet usage

Reduce simultaneous internet usage across all devices connected to your network. This might include:

  • Video and music streaming (including streaming via digital set top boxes)
  • Downloading / uploading large files
  • Torrent services
  • Background usage such as automated backups or synchronisation

If your internet connection is still running slowly, go to the next step.

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Step 2: Restart your modem

Remove the power cable from the back of your modem for 60 seconds, then plug it back in.

After approximately 2 minutes the lights on the modem should settle into a stable pattern.

If restarting your modem didn’t work, go to the next step.

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Step 3: Check your device

If multiple devices are affected, skip to step 4. If only one device has slow internet, try the steps below. If you need help completing any of them, consult the website of your device / software manufacturer, or see our mobile device guides.

  • Restart the device
  • Close any unnecessary programs and browser windows
  • Disable any browser extensions
  • Make sure your browser and operating system are up-to-date
  • Check if your device storage is approaching full capacity, which may affect its processing speed

If your device’s connection is still slow, check whether your antivirus or security program may be affecting it.

  1. Turn off your firewall / security program

  2. Test your internet speed

  3. Turn your firewall / security program back on

If your internet speed improved when you turned off your firewall or antivirus program, you have identified that the security settings are slowing down your connection.

Important: Do not leave your security settings turned off. Instead, contact the software manufacturer for help to reconfigure your firewall / security program to improve internet speed.

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Step 4: Check your cables

The condition of your cables can affect the speed and quality of your internet connection. Make sure the cable connecting your modem to your nbn™ equipment / wall socket is:

  • in good condition with no kinks
  • securely plugged in

If you have Cable internet, use a wrench to tightly screw in the cable that connects your modem / nbn™ Connection Box to the wall plate.

If you are still experiencing slow internet or dropouts, go to the next step.

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Step 5: Check your WiFi

To test whether your WiFi is causing the problem, use an ethernet cable to connect your computer directly to your modem.

If your computer’s connection speed improves, you have identified that your WiFi is the source of the problem. For help to optimise your WiFi setup, see WiFi connectivity and troubleshooting.

If this doesn’t resolve the problem, see Further help.

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Further help

Contact us and we’ll help you out. Advise the technician of the troubleshooting you’ve done.

nbn™: Call 1300 300 427

Optus Cable: Call 13 13 44

When you call, advise the technician what troubleshooting you have done. Keep in mind we may ask you to repeat some of the troubleshooting steps so that we can check the diagnostic responses from our network.

For general information on factors affecting network speeds, see How fast are Optus internet speeds?

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